What does cancer primarily involve in terms of cell behavior?

Cancer primarily involves a disease of cell proliferation where normal cells undergo uncontrolled growth. This abnormal behavior is characterized by the cells continuing to divide and multiply without the usual regulatory mechanisms that control cell growth and division. In normal physiology, cell division is tightly regulated; cells receive signals that instruct them to grow, stop, or die at appropriate times. In cancer, mutations or alterations in the cell's genetic material can lead to a loss of these controls, resulting in the defective cells multiplying uncontrollably.

This unchecked proliferation can lead to the formation of tumors, which can invade nearby tissues and potentially spread to other parts of the body through metastasis. The nature of cancer cells, therefore, lies in their ability to ignore signals that would typically terminate their lifecycle, leading to the accumulation of abnormal cells. Understanding this fundamental characteristic is essential in both diagnosing cancer and in developing treatment strategies that target the pathways involved in cell growth and survival.